Field of the invention
The present invention relates to mobile communication.
Related Art
In recent years, communication, i.e., machine type communication (MTC), occurring between devices or between a device and a server without a human interaction, i.e., a human intervention, is actively under research. The MTC refers to the concept of communication based on an existing wireless communication network used by a machine device instead of a user equipment (UE) used by a user. Meanwhile, since the existing LTE system has been designed for the purpose of supporting high-speed data communication, it has been regarded as an expensive communication method. However, the MTC may be widely used only when a price is low according to a characteristic thereof. Therefore, a method of reducing a bandwidth for MTC to be smaller than a system bandwidth has been examined for cost reduction.
Further, the MTC has recently attracted attention for the Internet of Things (IOT).
One way to reduce the cost of an IoT device is considering that the IoT device operates on a reduced bandwidth compared to the cell's system bandwidth.
IoT communication operating on such a reduced bandwidth is called NB (Narrow Band)-IoT communication.
In the NB-IoT, the subcarrier interval may be reduced differently from LTE. However, it is difficult to apply the reduced subcarrier spacing to the time division duplex (TDD) scheme.